The lesser kestrel (Falco naumanni) is one of the most endangered
bird species in Europe, and a captive breeding and reintroduction
project was established. A breeding project is vulnerable to pathogens,
eg, mycoplasmas, reducing the reproductive success and carrying the risk
to release pathogens with the birds to the wild. Therefore, 18 infertile
eggs and 43 dead inshell embryos of the breeding project, as well as 27
nestlings and 34 adult birds of the captive and 3 different free-ranging
populations were investigated for the occurrence of mycoplasmas by
culture and a Mycoplasma genus specific polymerase chain reaction. All
eggs, embryos, and hand-reared nestlings from the captive group were
negative. In contrast, all parent-reared nestlings and 88% of the adults
were positive. Mycoplasma falconis and unidentifiable mycoplasmas were
detected in all groups. Mycoplasma buteonis was found in the captive
population and only in 2 of the 3 free-ranging populations. Sequencing
the 16S ribosomal RNA gene of 6 randomly selected unidentified isolates
showed that 5 isolates were similar and most likely had been found
previously in a falcon from Germany. The remaining isolate demonstrated
a very high homology to unidentified Mycoplasma isolates obtained
previously from semen samples of raptors. The results suggest that these
isolates might represent 2 new species. Mycoplasmas seem not to play a
major role as pathogens in the breeding project, and there is no
evidence that releasing birds poses a risk to the free-ranging
population with regard to mycoplasmas. The study seems to be the first
to describe the occurrence and role of mycoplasmas in the lesser
kestrel.